This invention is directed to ophthalmic device materials. In particular, this invention relates to soft, high refractive index, acrylic ophthalmic device materials that are particularly suited for use as intraocular lens (xe2x80x9cIOLxe2x80x9d) materials.
With the recent advances in small-incision cataract surgery, increased emphasis has been placed on developing soft, foldable materials suitable for use in artificial lenses. In general, these materials fall into one of three categories: hydrogels, silicones, and acrylics.
Hydrogel materials have a relatively low refractive index, making them less desirable than other materials because of the thicker lens optic necessary to achieve a given refractive power. Silicone materials generally have a higher refractive index than hydrogels, but tend to unfold explosively after being placed in the eye in a folded position. Explosive unfolding can potentially damage the corneal endothelium and/or rupture the natural lens capsule. Acrylic materials are desirable because they typically have a high refractive index and unfold more slowly or controllably than silicone materials.
U.S. Pat. No. 5,290,892 discloses high refractive index, acrylic materials suitable for use as an IOL material. These acrylic materials contain, as principal components, two aryl acrylic monomers. The IOLs made of these acrylic materials can be rolled or folded for insertion through small incisions.
U.S. Pat. No. 5,331,073 also discloses soft acrylic IOL materials. These materials contain as principal components, two acrylic monomers that are defined by the properties of their respective homopolymers. The first monomer is defined as one in which its homopolymer has a refractive index of at least about 1.50. The second monomer is defined as one in which its homopolymer has a glass transition temperature less than about 22xc2x0 C. These IOL materials also contain a cross-linking component. Additionally, these materials may optionally contain a fourth constituent, different from the first three constituents, which is derived from a hydrophilic monomer. These materials preferably have a total of less than about 15% by weight of a hydrophilic component.
U.S. Pat. No. 5,693,095 discloses soft, foldable acrylic lens materials containing only two principal lens-forming components: one aryl acrylic hydrophobic monomer and one hydrophilic monomer. The materials comprise at least about 90% by weight of the two principal monomeric components.
According to the present invention, high refractive index, acrylic ophthalmic device materials are produced by a two-step method. In the first step, at least one aryl acrylic hydrophobic monomer is combined with up to a total of about 30% by weight of one or more compounds of the formula 
wherein
X is H or CH3; and
n is 1-4;
and cured to form a copolymer containing pendant oxirane groups. In the second step, the copolymer containing pendant oxirane groups formed in step one is reacted with one or more compounds of the formula
Wxe2x80x94Txe2x80x94Hxe2x80x83xe2x80x83(III)
wherein
W is H, CH3(CH2)a, or Z(OCH2CH2)b;
b is 1-5;
Z is H, CH3, or CH3(CH2)a;
a is 0-3; and
T is O, N, S; provided that if Txe2x89xa0O, then Wxe2x89xa0H;
to form the ophthalmic device material of the present invention. The resulting material is suitable for use in ophthalmic devices, such as intraocular lenses, contact lenses, keratoprostheses, corneal rings, and corneal inlays.